Revert "travis: add a debug print to debug SEGV on Travis"

This reverts commit 96c1e4bb3d0b83d16b701015f8546bb889e78cf1.

We found the cause of the SEGV. grn_get_version() cannot be worked with
"git clone --depth 1 .../groonga.git" repository. It had been fixed in
groonga.